The objective of the proposed research is to compare the problem solving methods of individuals who are skilled and unskilled in dealing with a particular class of problems, and to describe the changes in problem solving methods employed by individuals as a function of various types of experience. The training procedure will consist of immediate feedback with or without advice, a rationale for the feedback. The task will evaluate or choose the best move in single-pawn endings in chess. The expectation is that the development of skill will be accompanied by an increase in the use of pattern perception, such that the patterns serve as subgoals. Three procedures will be used to assess the perceptual patterns, (a) speed of decision, (b) speed of recognition, and (c) protocols. The rationale for the speed measures is that cognitive structures and operations can be inferred from the time it takes to complete a task. Finally, there will be computer simulation of the performance of skilled chess players and the change in the performance of unskilled individuals with experience.